Control valve

ABSTRACT

A control valve for use in a split braking system with a split master cylinder including a housing having a divider member therein provided with a flow passage for one of the supplied fluid pressures. A proportioning member is movable in the divider member controlling the flow passage to normally establish an applied fluid pressure in a predetermined ratio with the one supplied fluid pressure. The flow passage also includes a branch or bypass portion normally subjected to the applied fluid pressure, and a warning or switch-operating piston has one end slidable in the divider member branch portion normally subjected to the applied fluid pressure and the other end thereof slidable in the housing subjected to the other supplied fluid pressure. A centering piston is subjected to the one supplied fluid pressure and engaged with said housing and switch piston normally maintaining said switch piston in a centered position, and said switch piston is movable upon the failure of the other supplied fluid pressure toward a translated position opening the branch portion to effect open pressure fluid communication therethrough between the one supplied and applied fluid pressures to obviate the proportioning function of the proportioning member. This invention relates in general to dual or split braking systems and in particular to a combustion driver warning, proportioning and bypass valve for utilization therein.

United States Patent [72] Inventor Stanley I... Stokes Florissant, Mo.[21] Appl. No. 5,468 [22] Filed Jan. 26, 1970 I 45] Patented Aug. 3,1971 [73] Assignee Wagner Electric Corporation Newark, NJ.

[54] CONTROL VALVE 10 Claims, 4 Drawing Figs. [52] US. Cl .i 303/6 C,60/545 E, 188/151 A, 188/349, 200/82 D, 303/84 A [51] Int. Cl B60t 8/26,B60t ll/34, B60t 17/22 [50] Field of Search 303/6, 6 C, 84, 84 A;60/545; 188/151 A, 349; 200/82 D [56] References Cited UNITED STATESPATENTS 3,469,889 9/1969 Bueler 303/6 C 3,472,559 10/ 1969 Bueler...303/6 C 3,480,333 11/1969 Stelzer... 303/84 A X 3,532,390 10/1970 Bueler303/6 C Primary Examiner-Milton Buchler Assistant Examiner-John J.McLaughlin Anorney.loseph E. Papin ABSTRACT: A control valve for use ina split braking system with a split master cylinder including a housinghaving a divider member therein provided with a flow passage for one ofthe supplied fluid pressures. A proportioning member is movable in thedivider member controlling the flow passage to normally establish anapplied fluid pressure in a predetermined ratio with the one, suppliedfluid pressure. The flow passage also includes a branch or bypassportion normally subjected to the applied fluid pressure, and a warningor switch-operating piston has one end slidable in the divider memberbranch portion normally subjected to the applied fluid pressure and-theother end thereof slidable in the housing subjected to the othersupplied fluid pressure. A centering piston is subjected to the onesupplied fluid pressure and engaged with said housing and switch pistonnormally maintaining said switch piston in a centered position, and saidswitch piston is movable upon the failure of the other supplied fluidpressure toward a translated position opening the branch portion toeffect open pressure fluid communication therethrough between the onesupplied and applied fluid pressures to obviate the proportioningfunction of the proportioning member.

This invention relates in general to dual or split braking systems andin particular to a combustion driver warning, pro portioning and bypassvalve for utilization therein.

CONTROL VALVE SUMMARY In past control valves used with a split mastercylinder in a split braking system, such as disclosed in my copendingapplication Ser. No. 861,358 filed Sept. 26, 1969, a proportioningmember was provided to proportion one of the supplied fluid pressures ofthe split master cylinder in one of the split systems to effect aproportionally reduced applied fluid pressure in the one split systemconnected with the vehicle rear brakes; however, in the event of thefailure of the other supplied fluid pressure of the split mastercylinder in the other of the split systems, it was desirable to bypassthe one supplied fluid pressure around the proportioning member toobviate the proportioning function thereof and utilize the maximumavailable fluid pressure in the one split system for braking under theseemergency conditions. This bypassing function was accomplished by anindicating member or switch-operating piston which was provided tocompare the magnitudes of the one and other supplied fluid pressures.The switch operating piston was movable toward a translated or bypassingposition in response to the one supplied fluid pressure acting thereonupon the failure of the other supplied fluid pressure to bypass the onesupplied fluid pressure around the proportioning member in order toobviate the proportioning function thereof.

The present control valve is provided with a divider member having aflow passage therein for the one supplied fluid pressure, and aproportioning member is movable in said flow passage to normallyestablish the applied fluid pressure in a predetermined ratio with theone supplied fluid pressure. An indicator or switch-operating piston hasone end slidable in the divider member and normally subjected to theapplied fluid pressure while the other end thereof is subjected to theother supplied fluid pressure, and a centering piston which is normallysubjected to the one supplied fluid pressure normally maintains saidindicator member in a centered position. The indicator member is movablein response to the applied fluid pressure acting on the one end thereofupon the failure of the other supplied fluid pressure acting on theother end thereof toward a translatedor bypassing position to effectopen pres sure fluid communication through the divider member betweenthe one supplied and applied fluid pressures thereby obviating theproportioning function of the proportion member.

RELATED PATENTS This patent application is related to U.S. Pat. No.3,464,741 issued to Edward J. Falk on Sept. 2, I969, U.S. Pat. No.3,450,433 issued to Richard C. Bueler on June 17, 1969, and U.S. Pat.No. 3,448,230 issued to Richard C. Bueler on June 3, 1969, said patentsbeing assigned to the common assignee of this patent application whichis a patentably distinct improvement. DRAWING DESCRIPTION In thedrawings wherein like numerals refer to like parts wherever they occur:

FIG. I is a sectional view illustrating a control valve embodying thepresent invention in cross section;

, FIG. 2 is a partial sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged fragmentary view taken from FIG. 1; and

FIG. 4 is a graphical representation of the applied or output fluidpressures effected by the proportioning valve of FIG. 1 in response tothe input or supplied fluid pressure. f

Referring now to the drawings in detail and in particular to FIG. 1, acontrol valve 1 is provided with a housing 2 which is adapted for directconnection with the housing of a dual or split'system master cylinder(not shown); however, if desired, said control valve can be remotelypositioned with respect to said master cylinder, as is well known in theart. The housing 2 is provided with stepped bores 3, 4 in axialalignment with stepped counterbores 5, 6 and 7, and shoulders 8, 9, 10are provided in said housing between the stepped bore 4 and counterbore5, the counterbores 5 and 6, and the counterbores 6 and 7, respectively.Inlet ports 11, 12, which are adapted for connection with the separatefluid pressure generating chambers of a split system master cylinder,are provided in the housing 2 intersecting with the bore 3 adjacent itsrightward end and with the counterbore 6 adjacent to its midportion,respectively, and an outlet port 13, which is adapted for connectionwith one of the rear and from vehicle brakes (not shown), is alsoprovided in said housing intersecting with the counterbore 7. A closuremember end plug 14 is threadedly received in the leftward or open end ofthe counterbore 7 having a centrally located guide bore 15 therein, anda seal 16 is also positioned in said closure member about said guidebore.

Referring now also to FIG. 2, a cross-bore 17 isalso provided in thehousing 2 having one end intersecting with the largerstepped bore 4 andthe other end thereof connecting with a cross-counterbore 18 which isthreaded at its open end to receive an electrical switch 19, to bediscussed hereinafter.

Referring now to FIGS. 1 and 3, a sleeve or divider member, indicatedgenerally at 20, is provided with a sleeve or body portion 21 whichextends coaxially through the housing counterbore 7, and a peripheral orannular chamber 22 is defined between said housing counterbore 'anddivider body connected in open pressure fluid communication with theoutlet port 13 at all times. The divider body 21 is provided withopposed end portions 23, 24 in abutting engagement between the interiorend of the closure member 14 and the housing shoulder 10, and peripheralseals 25, 26 are carried in said divider bodyadjacent to the opposed endportions 23, 24 in sealing engagement with the closure member 14 and thehousing counterbore -7. An extension 27 is integrally provided on thedivider body end portion 24 extending coaxially through the housingcounterbore 6 partially into the counterbore 5 and having a free end orabutment 28 thereon terminating adjacent to the housing shoulder 9. Thedivider body 21 is provided with a bore 29 interposed between acounterbore 30 whichextends coaxially through the extension 27intersecting with the free end 28 thereof and steppedcounterbores 31, 32and 33 which extend coaxially through said divider portion. A shoulder34 is provided on the divider body 21 between the bore 29 andcounterbore 30, and shoulders 35, 36 are also provided on said dividerbody between said bore 29 and counterbore 31 and between thecounterbores 31 and 32, respectively. A connecting passage 37 isprovided in the divider body 21 connecting the counterbore 31 in openpressure fluid communication with the housing annular chamber 22 at alltimes, and another connecting passage 38 is provided in said body havingone end connected in open pressure fluid communication with the bodycounterbore 33 and the other end thereof intersecting with the dividerbody rightward or opposed end portion 24 in open pressure fluidcommunication with the inlet port 12 through the housing counterbore 6at all times. The connecting passage 38, the body counterbores 31, 32,33 and the connecting passage 37 of the divider body 21 define a flowpassage, indicated generally at F, which is connected with the inletport 12 through the housing counterbore 6 and with the outlet port 13through the annular chamber 22, and the bore and counterbore 29, 30 ofthe divider body 21 define a bypass passage, indicated generally at B,which is connected in parallel, shunting or bypass relation with theflow passage F being connected with said inlet port 12 through thehousing counterbores 5, 6.

A metering or proportioning member, indicated generally at 39, isprovided with a head portion 40 integrally formed with opposed reducedextensions or stem portions 41, 42. The stem portion 41 extendsthroughthe closure member seal 16 in sealing engagement therewith intosliding and guiding engagement with the closure member bore 15, and theextension 42 is slidably and guidably received in the divider body bore29. A shoulder or abutment 43 is provided on the proportioning piston 39between the head portion 40 and extension 42, and a proportioning ormetering spring 44 is precompressed between said head portion and aretainer 45 to respectively urge said abutment and retainer intoengagement with the divider body shoulder 35 and the interior end of theclosure member 14, respectively. An annular peripheral groove 46 isprovided in the proportioning pistonhead 40 having a base wall 47interposed between opposed radially extending sidewalls 48, 49, saidsidewall 49 defining a valve member for engagement with an annularsealing or seating member 50. Sealing member 50 is provided with anannular portion 51 defining an aperture therethrough and radially spacedfrom the groove base wall 47 and interposed between opposed sides 52,53. The seal side 53 is normally seated in abutment with the dividerbody shoulder 36 and also defines a valve seat for engagement with thevalve member or groove sidewall 49. The seal 50 is alsoprovided with anannular peripheral lip 54 in sealing engagement with the divider bodycounterbore 32, and a plurality of radially extending flow passages orribs 55 are provided between the seal side 53 and lip 54, said returnflow passages being normally closed upon the sealing engagement of saidlip with said divider body counterbore. The housing counterbores 5, 6and the divider body counterbores 32, 33 which are interconnected by theconnecting passage 38 define an inlet chamber 56 connected in openpressure fluid communication with the inlet port 12 at all times, andthe divider body bore 29 and counterbores 30, 31, and the annularchamber 22 which are interconnected by the connecting passage 37 definean outlet chamber 57 which is connected in open pressure fluidcommunication with the outlet port 13 at all times. It should also benoted that the sealing engagement of the groove sidewall or valve member49 with the valve seat 53, as discussed hereinafter, defines aneffective area A on the proportioning piston 39 which is subjected tothe fluid pressure at the outlet port 13, and another effective area A,is provided by the sealing engagement of the proportioning piston stem41 with the closure member seal 16 and subjected to the atmosphere inthe closure member bore 15 at all times, said area A, being opposed toand predeterminately greater than the area A A centering member orpiston, indicated generally at 58, is slidably received in the housingcounterbore having opposed ends or abutment surfaces 59, 60, and anaxially extending bore 61 is provided through said centering pistonbetween said opposed ends thereof. A sealing member, such as the O-ringseal 62, is sealably engaged between the housing counterbore 5 and theleftward end 59 of the centering piston 58, and the rightward opposedend thereof is normally engaged with the housing shoulder 8, said O-ringseal and leftward end of said centering piston defining an annulareffective area A subjected to the fluid pressure at the inlet port 12 atall times.

A reciprocal switch actuating or indicating member, such as the pistonindicated generally at 63, is shown in its centered or normal operatingposition in the housing 2 having opposed extensions, flanges or endportions 64, 65 thereon. The switch piston end portion 64 is slidablyreceived in the housing stepped bore 3, and 'an annular peripheral seal66 is carried on said switch piston end portion in sealing engagementwith said housing stepped bore. The sealing engagement of the seal 66with the housing stepped bore 3 defines an effective cross-sectionalarea A on the end portion 64 which is subjected to the fluid pressure atthe inlet port 11 at all times, and an inlet chamber 67 is defined insaid housing stepped bore between the rightward end wall thereof andsaid end portion in open pressure fluid communication with said inletport at all times. The switch piston 63 is slidably received in thecentering piston bore 61 and extends through the O-ring seal 62 insealing engagement therewith, and an annular shoulder or abutment 68 isprovided on said switch piston for driving or centering engagement withthe rightward end 60 of the centering piston 58. The switch piston endportion 65 is slidably received in the counterbore 30 of the dividerbody extension 27 having a free end 69 thereon in said extension bore,and an O-ring seal 70 is carried in said switch piston end portionadjacent to said free end thereof normally in sealing engagement withsaid extension bore. The sealing engagement of the O- ring seal 70 withthe extension bore 30 defines another effective cross-sectional area Aon the switch piston end portion 65 which is subjected to the fluidpressure at the outlet port 13. It should be noted that the sealingengagement of the switch piston seal 70 with the divider bodycounterbore 30 normally closes the bypass passage B interruptingpressure fluid communication between the inlet chamber 56 and the outletchamber 57 through said bypass passage. It should also be noted that thearea A is opposed to and less than the area A.,, and that the area A isadditive to and greater than the area A however, the sum of the areas AA is greater than the area A Referring now to FIGS. 1 and 2, the switchpiston 63 is provided with a switch-positioning portion or land 71 whichis substantially aligned with the housing cross-bore 17 when said switchpiston is in its centered position, as shown, and peripheral cam facesor surfaces 72, 73 are also provided on said switch piston on opposedsides of said land. The switch 18, as previously mentioned, is providedwith a conductive closure or plug member 74 threadedly received in theopen end of the housing cross-bore 18, and a metal terminal 75 extendsthrough said plug member being insulated therefrom, said terminal havingan exterior end for connection in an electrical circuit of a type wellknown to the art for selectively energizing a driver warning or dashlamp (not shown). A conductive switch member 76 is slidably received ina bore 77 provided in the switch plug 74 and in electrical contact orengagement therewith, said switch member being provided with a followerportion or end 78 extending through the housing cross-bore 17 intofollowing engagement with the land 71 and cams 72, 73 of the switchpiston 63. The switch member 76 is also provided with an upper end 79defining a contact for electrical contact or conductive engagement withthe interior end of the terminal 75, and a switch spring 80 urges thecontact 79 from said terminal interior end and the follower end 78toward engagement with the switch piston 63.

in the operation with the component parts of the control valve 1positioned as shown in the drawings and as described hereinafter,separately supplied or input fluid pressures P P normally havingsubstantially equal magnitudes are transmitted upon actuation of thesplit system master cylinder (not shown) to the inlet ports 11, 12,respectively, of the control valve 1. The input fluid pressure P, flowsfrom the inlet port 11 into the inlet chamber 67 acting on the switchpiston area A., to establish a force P, A.,, and the input fluidpressure P flows from the inlet port 12 into the housing counterbores5,6 acting on the centering piston area A to establish a force P A inopposition to the force P, A, and urging said centering piston towardengagement with the housing shoulder 8 and the switch piston abutment68. The fluid pressure P also flows from the housing counterbore 6through the divider body connecting passage 38, the counterbores 32, 33,annular groove 46 of the proportioning piston and the divider bodycounterbore 31 and connecting passage 37 into the annular chamber 22 toestablish an applied or output fluid pressure Po at the outlet port 13.The applied or output fluid pressure Po so established in the outletchamber 57 acts on the effective area A of the switch piston 68 toestablish a force Po A in opposition to the force P, A, and additive tothe switch piston force P A Since the sum of the areas A A is greaterthan the area A.,, as mentioned hereinbefore, the additive forces Po A PA are greater than the opposing force P A to normally obviate leftwardtranslatory movement of the switch piston 63 from its centered position.Further, since the force P A urges the centering piston 58 intoengagement with the housing shoulder 8, it is also apparent that theforce F, A, is greater than the force Po A to normally oppose rightwardtranslatory movement of the piston 60 from its centered position sincethe area A, is greater than the area A The input fluid pressure P, actson the input effective area A,-A of the proportioning piston 39 toestablish an input force P- (A,- A- 1) and the output fluidpressureP.,acts on the output effective area A, of said proportioning piston toestablish an output force Po A, opposed to the input force P (A,-A).Since the input and output fluid pressures P,(A,- A Since the input andoutput fluid pressures P P0 are initially equal throughout the range OR,as shown on the line ORS in the graph of FIG. 4, and since the outputarea A, is greater than the input area A,-A of the proportioning piston39, it is obvious that the output force Po A, is greater than the inputforce F, (A,-A,); however, the compressive force Fc of the meteringspring 44 is additive to the input force P (A,-A and thereby movement ofthe proportioning piston 39 is prevented until the input and outputfluid pressures P P0 exceed the predetermined value R as shown on theline OR in the graph of FIG. 4. When the predetermined value R of theinput and output fluid pressures P P0 is attained, the output force PoA, overcomes the additive input and spring forces P, (A,-A), Fc to movethe proportioning piston 39'from its normal position in a leftwarddirection toward an operating or metering position against thecompressive force Fc of the metering spring 44. This leftward movementof the proportioning piston 39 initially moves the valve member 49thereof into lapped engagement with the rightward face or seat 53 of thesealing or valve element 50 to interrupt pressure fluid communicationbetween the inlet and outlet ports l2, 13 through the flow passage F andisolate the input fluid pressure P from the output fluid pressure Po.

it is obvious that the increases in the magnitude of the input fluidpressure P in excess of the predetermined value R, as illustrated by theline RS in the graph of FIG, 4, will result in proportionally reduced ormetered increases in the output fluid pressure Po, as illustrated by theline RT. For instance, when the input fluid pressure P, is furtherincreased to a value in excess of the predetermined value R, the inputforce P (A,-A) is correspondingly increased and additive to the springforce Fc to overcome the output force Po A,; therefore, theproportioning piston 39 is moved rightwardly toward a metering positiondisengaging the proportioning piston valve member 49 from the sealingmember seat 53 to effect a metered application of the increased inputfluid pressure P through the proportioning piston groove 46 into theoutlet chamber 57 and therefrom to the outlet port 13 to effect aproportional or ratioed increase in the the output fluid pres sure Po,as shown by the line RT in the graph of FIG. 4 wherein itta aam Ofcourse, the increased output fluid pressure P0 in excess of thepredetermined value R effects a corresponding increase in the outputforce Po A,, and when the increased output force Po A, attains anincreased value substantially equal to the additive input force andspring force P (A,A Fc, the proportioning piston 39 is again movedleftwardly to reposition the valve member 49 thereof in lappedengagement with the sealing member seat 53 closing the proportioningpiston groove 46 to again isolate the input and output fluid pressures PP0. it is, of course, obvious that the proportioning piston will beresponsive to further increases in the input fluid pressure P to effectfurther proportional increases in the output fluid pressure P0 in thesame manner as previously described.

When the split system master cylinder is deactuated, the input fluidpressures P,, P are vented to atmosphere which eliminates the forces P Aand P, A acting on the centering and switch pistons 58, 63 as well asthe input force P (A,A acting on the proportioning piston 39. Uponelimination of the input fluid pressure P,, the output fluid pressure Poacting on the sealing member 50 displaces the lip 54 thereof fromsealing engagement with the divider body counterbore 32, and in thismanner the applied or output fluid pressure Po returns from the outletport 13 through the outlet chamber 57, the

return flow passages 55 in said sealing member and between the displacedlip thereof and said divider body counterbore into the inlet chamber 56to the inlet port 11. When the output fluid pressure Po is so reduced tocorrespondingly reduce the output force Po A, to a value less than thatof the metering spring force Fc, the metering spring 44 moves theproportioning piston 39 rightwardly to its original position with theabutment 43 thereof in engagement with the divider member shoulder 35displacing the proportioning piston valve member 49 from the sealingmember seat 53 and thereby opening the proportioning piston groove 46 toagain establish open pressure fluid communication between the inlet andoutlet ports l2, 13 through the flow passage F and effect completeelimination of the output fluid pressure P0,

in the event of the failure of the input fluid pressure P, due to amalfunction of the split system master cylinder or other leaks or thelike, it is, of course, desirable to obviate the metering function ofthe proportioning piston 39 and effect the application of the inputfluid pressure P, through the bypass passage B to establish an unalteredor unmetered output fluid pressure Po at the outlet port 13 in order toutilize the maximum available fluid pressure for energizing the vehiclebrake set connected with said outlet port under such emergencyconditions; therefore, when the magnitude of the applied fluid pressurePo exceeds that of the failed input fluid pressure P,

by a predetermined value, the force Po A acting on the switch piston 63will displace said switch piston rightwardly toward its rightwarddisplaced or translated position engaging the switch piston end portion64 with the end wall of the housing stepped bore 3 since the force P, A,normally opposing such translatory movement is eliminated upon thefailure of the input fluid pressure P,. This rightward translatorymovement of the switch piston 63 also moves the leftward end portion 65thereof toward a displaced or translated position in the divider membercounterbore 30 disengaging the switch piston seal 70 therefrom to openthe bypass passage B between the inlet and outlet ports l2, 13. In thismanner, the input fluid pressure P, flows from the inlet port 12 throughthe housing counterbores 5, 6, the divider body bore and counterbores29, 30 and the connecting passage 37 into the annular chamber 22 andtherefrom to the outlet port 13 in bypass relation with theproportioning piston 39 to obviate metering or proportioning actuationthereof, and it is, of course, obvious that the bypassed output fluidpressure Po so established at the outlet port 13 is equal to the inputfluid pressure P, at the inlet port 12 when the bypass passage B is opento effect the application of the maximum available fluid pressure to thevehicle brake set connected with said outlet port under the emergencyconditions. Further, the rightward translatory movement of the switchpiston 63 also moves the cam surface 72 thereof rightwardly toward aposition driving the switch member 76 upwardly against the compressiveforce of the switch spring to engage the contact 79 with the interiorend of the terminal 74 and in this manner complete the electricalcircuit for energizing the driver warning or dash lamp (not shown).

The control valve 1 functions in substantially the same manner tocomplete the electrical circuit for energizing the driver warning ordash lamp in the event of the alternative failure of the supplied fluidpressure P Failure of the fluid pressure P,, of course, eliminates theforces P A and Po A acting on the centering and switch pistons 58, 63wherein the force of the supplied fluid pressure P, acting on the switchpiston area A, effects the leftward translatory movement of the switchpiston 63 to engage the end 65 of said switch posi tion with the dividerbody shoulder 34 which defines the leftward translatory position of saidswitch piston, said centering piston being concertedly movable with saidswitch piston. During the leftward translatory movement of the switchpiston 63, the cam surface 73 thereof drivingly engages the switchmember 76 to actuate the switch 19, as previously described.

What i claim is:

1. in a split braking system having a split master cylinder forsupplying separate fluid pressures to said split braking system;

a control valve comprising a housing adapted to receive the separatesupplied fluid pressures, a divider member in said housing including apressure fluid flow passage therethrough for one of the supplied fluidpressures, proportioning means movable in said divider member forcontrolling said flow passage, said proportioning means being movable inresponse to the one supplied fluid pressure toward a metering positionin said flow passage to effect a metered applied fluid pressure throughsaid flow passage in a predetermined ratio with the one supplied fluidpressure, and a bypass passage in said divider member having one endconnected with said flow passage and subjected to the applied fluidpressure and the other end thereof subjected to the one supplied fluidpressure, indicator means subjected to the applied fluid pressure andthe other of the supplied fluid pressure and movable in said dividermember for controlling said bypass passage, said indicator means beingmovable in response to the applied fluid pressure in said bypass passageacting thereon from a normal centered position toward one of opposedtranslated positions in said housing to open said bypass passage andestablish pressure fluid communication therethrough between the onesupplied fluid pressure and the applied fluid in bypass relation withsaid proportioning member to obviate the metering actuation thereof inthe event of the failure of the other supplied fluid pressure acting onsaid indicator means, and centering means movable in said housing forengagement with said housing and with said indicator means and subjectedto the one supplied fluid pressure, said centering means being urged inresponse to the one supplied fluid pressure acting thereon towardengagement with said housing and said indicator means to oppose movementof said indicator means from its centered position toward the other ofits translated positions in response to the other supplied fluidpressure acting thereon.

2. A control valve according to claim 1, comprising first and secondopposed end portions on said indicator means movable in said bypasspassage and said housing and subjected to the applied fluid pressure andthe other supplied fluid pressure, respectively, said first end portionnormally interrupting pressure fluid communication through said bypasspassage between the one supplied fluid pressure and the applied fluidpressure when said indicator means is in its centered position, saidindicator means being movable to its one translated position in responseto the applied fluid pressure acting on said first end portion upon thefailure of the other supplied fluid pressure acting on said second endportion, and said first end portion being movable to a bypassingposition opening said bypass passage to establish the pressure fluidcommunication therethrough between the one supplied fluid pressure andthe applied fluid pressure upon the movement of said indicator means toits one translated position.

3. A control valve according to claim 2, comprising seal means normallyengaged between said first end portion and said bypass passage to closesaid bypass passage and interrupt pressure fluid communicationtherethrough between the one supplied fluid pressure and the appliedfluid pressure, said seal means being disengaged from one of said firstend portion and said bypass passage upon the movement of said first endportion to its bypassing position.

4. A control valve according to claim 3, wherein said seal means iscarried on said first end portion and disengaged from said bypasspassage upon the movement of said first end portion to its bypassingposition.

5. A control valve according to claim 1, comprising seal means normallyengaged between said indicator means and said bypass passage to closesaid bypass passage and interrupt pressure fluid communicationtherethrough between the one supplied fluid pressure and the appliedfluid pressure, said seal means being disengaged from one of saidindicator means and bypass passage upon the movement of said indicatormeans to its one translated position to open said bypass passage andestablish the pressure fluid communication therethrough between the onesupplied fluid pressure and the applied fluid pressure.

6. A control valve according to claim 5, wherein said seal means iscarried on said indicator means and disengaged from said bypass passageupon the movement of said indicator means to its one translatedposition.

7. A control valve according to claim 1, comprising a pair of steppedbores in said divider member defining a portion of said flow passage,said proportioning means being movable in one of said stepped bores, avalve seat on said divider member between said stepped bores forengagement with said proportioning means, said proportioning means beinginitially movable to its isolating position into engagement with saidvalve seat to isolate the one supplied fluid pressure in said onestepped bore from the applied fluid pressure in the other of saidstepped bores and being thereafter further movable to its meteringposition disengaged from said valve seat to effect the metered increasein the applied fluid pressure, and said one end of said bypass passagebeing connected with said other stepped bore.

8. A control valve comprising a housing, a divider member in saidhousing and defining with said housing a pressure fluid flow passagetherethrough for one of separate fluid pressures supplied to saidhousing, a pair of stepped bores in said divider member defining aportion of said flow passage, an annular shoulder on said divider memberbetween said stepped bores, valve seating means about said flow passageand normally engaged with said shoulder, a proportioning piston movablein one of said stepped bores and having valve means thereon extendinginto the other of said bores for engagement with said valve seatingmeans to control the application of the one supplied fluid pressure fromsaid one stepped bore to said other stepped bore, resilient meansengaged with said proportioning piston and normally urging said valvemeans toward a position disengaged from said valve seating means,opposed first and second effective areas on said proportioning pistonfor respective subjection to the one supplied fluid pressure and theapplied fluid pressure, said proportioning piston being initiallymovable against the force of said resilient means in response to the onesupplied fluid pressure and applied fluid pressure of a predeterminedvalue respectively acting on said first and second areas toward aposition engaging said valve means with said seating means and isolatingthe one supplied fluid pressure in said one stepped bore from theapplied fluid pressure in said other stepped bore, said proportioningpiston also being thereafter further movable against the applied fluidpressure acting on said second area in response to increases in the onesupplied fluid pressure acting on said first area and assisted by theforce of said resilient means toward a metering position disengagingsaid valve means from said seating means to effect a metered increase inthe applied fluid pressure in a predetermined ratio with the increasedone supplied fluid pressure in excess of the predetermined value, abypass passage in said divider member having one end connected with saidother stepped bore and the end thereof subjected to the one suppliedfluid pressure, indicator means movable between a centered position andopposed translated positions in said housing for indicating a failure ofthe one supplied fluid pressure and the other of the supplied fluidpressures including a first end portion movable in said housing andhaving a third effective area thereon subjected to the other suppliedfluid pressure, a second end portion on said indicator means and opposedto said first end portion, said second end portion being movable in saiddivider member for controlling pressure fluid communication through saidbypass passage between the one supplied fluid pressure and applied fluidpressure, a fourth effective area on said second end portion opposed tosaid third area and subjected to the applied fluid pressure, saidindicator means being movable from its centered position toward one ofits translated positions in response to the applied fluid pressureacting on said fourth area in the event of the failure of the othersupplied fluid pressure acting on said third area, and said second endportion being movable toward a bypassing position in said bypass passageestablishing open pressure fluid communication therethrough between theone supplied fluid pressure and the applied fluid pressure in bypassrelation with said proportioning piston to obviate the metering functionthereof when said indicator means is moved to its one translatedposition, a centering piston movable in said housing for engagement withsaid housing and said indicator means, and a fifth area on saidcentering piston opposed to said third are and subjected to the onesupplied fluid pressure, said centering piston being urged in responseto the one supplied fluid pressure acting on said fifth area towardengagement with said housing and said indicator means to oppose movementof said indicator means from its centered position toward the other ofits translated positions in response to the other supplied fluidpressure acting on said third area.

9. In a split braking system having a split master cylinder forsupplying separate fluid pressures to said split braking system; acontrol valve comprising a housing adapted to receive the separatesupplied fluid pressures, a divider member in said housing and definingtherewith inlet and outlet chambers, said inlet chamber being subjectedto one of the supplied fluid pressures, proportioning means movable insaid divider member between said inlet and outlet chambers forcontrolling the application of the one supplied fluid pressure from saidinlet chamber to said outlet chamber, said proportioning means beinginitially movable in response to the one supplied fluid pressure in saidinlet chamber and the applied fluid pressure in said outlet chamber of apredetermined value toward a position isolating the one supplied fluidpressure in said inlet chamber from the applied fluid pressure in saidoutlet chamber and being thereafter further movable in response toincreases in the one supplied fluid pressure in said inlet chambertoward a metering position efi'ecting a metered increase in the appliedfluid pressure in said outlet chamber in a predetermined ratio with theincreased one supplied fluid pressure in excess of the predeterminedvalue, a bypass passage in said divider member having one end connectedwith said outlet chamber and subjected to the applied fluid pressure andthe other end thereof connected with said inlet chamber and subjected tothe one supplied fluid pressure, another inlet chamber in said housingsubjected to the other of the supplied fluid pressures, indicator meansincluding an end portion movable in said housing and subjected to theother supplied fluid pressure in said other inlet chamber, another endportion opposed to said first-named end portion movable in said dividermember for controlling pressure fluid communication through said saidbypass passage between the one supplied fluid pressure in said firstnamed inlet chamber and the applied fluid pressure in said outletchamber, said other end portion being subjected to the applied fluidpressure in said bypass passage, said indicator means being movable froma normal centered position toward one of opposed translated positions insaid housing in response to the applied fluid pressure acting on saidother end portion in the event of the failure of the other suppliedfluid pressure in said other inlet chamber acting on said one endportion, and said other end portion being movable toward a positionopening said bypass passage and establishing pressure fluidcommunication therethrough between the one supplied fluid pressure insaid first named inlet chamber and the applied fluid pressure in saidoutlet chamber in bypass relation with said proportioning means toobviate the metering actuation thereof when said indicator means ismoved to its one translated position, and centering means movable insaid housing for engagement with said housing and said indicator meansand subjected to the one supplied fluid pressure in said first-namedinlet chamber, said centering means being urged in response to the onesupplied fluid pressure in said first named inlet chamber acting thereontoward engagement with said housing and with said indicator means tooppose movement of said indicator means from its centered positiontoward the other of its translated positions in response to the othersupplied fluid pressure in said other inlet chamber acting on said oneend portion.

10. A control valve comprising a housing having a pair of inlet portsand an outlet port, a divider member in said hou smg including passagemeans connected between one of said inlet ports and said outlet port,proportioning means movable in said passage means for controlling theapplication of fluid pressure therethrough from said one inlet port tosaid outlet port, said proportioning means being initially movable inresponse to fluid pressures at said one inlet port and said outlet portof a predetermined value toward a position in said passage meansisolating the respective fluid pressures at said one inlet port and saidoutlet port and being thereafter further movable in response toincreases in the fluid pressure at said one inlet port toward a meteringposition effecting a metered increase in the fluid pressure at saidoutlet port in a predetermined ratio with the increased fluid pressureat said one inlet port, and bypass passage means in said divider memberhaving one end connected with said first named passage means andsubjected to the fluid pressure at said outlet port and the other endthereof connected with said one inlet port, indicator means including anend portion movable in said housing and subjected to the fluid pressureat the other of said inlet ports, another end portion opposed to saidfirst named end portion movable in said divider member for controllingpressure fluid communication through said bypass passage means betweensaid one inlet port and said outlet port and subjected to the fluidpressure at said outlet port, said indicator means being movable from anormal centered position toward one of opposed translated positions insaid housing in response to the fluid pressure at said outlet portacting on said other end portion in the event of the failure of thefluid pressure at said other inlet port acting on said one end portion,and said other end portion being movable toward a position in saidbypass passage establishing open pressure fluid communicationtherethrough between the fluid pressures at said one inlet port and saidoutlet port in bypass relation with said proportioning means to obviatethe metering actuation thereof when said indicator means is moved to itsone translated position, and centering means movable in said housing forengagement with said housing and said indicator means and subjected tothe fluid pressure at said one inlet port, said centering means beingurged in response to the fluid pressure at said one inlet port actingthereon toward engagement with said housing and with said indicatormeans to oppose movement of said indicator means from its centeredposition toward the other of its translated positions in response to thefluid pressure at said other inlet port acting on said one end portion.

1. In a split braking system having a split master cylinder forsupplying separate fluid pressures to said split braking system; acontrol valve comprising a housing adapted to receive the separatesupplied fluid pressures, a divider member in said housing including apressure fluid flow passage therethrough for one of the supplied fluidpressures, proportioning means movable in said divider member forcontrolling said flow passage, said proportioning means being movable inresponse to the one supplied fluid pressure toward a metering positionin said flow passage to effect a metered applied fluid pressure throughsaid flow passage in a predetermined ratio with the one supplied fluidpressure, and a bypass passage in said divider member having one endconnected with said flow passage and subjected to the applied fluidpressure and the other end thereof subjected to the one supplied fluidpressure, indicator means subjected to the applied fluid pressure andthe other of the supplied fluid pressure and movable in said dividermember for controlling said bypass passage, said indicator means beingmovable in response to the applied fluid pressure in said bypass passageacting thereon from a normal centered position toward one of opposedtranslated positions in said housing to open said bypass passage andestablish pressure fluid communication therethrough between the onesupplied fluid pressure and the applied fluid in bypass relation withsaid proportioning member to obviate the metering actuation thereof inthe event of the failure of the other supplied fluid pressure acting onsaid indicator means, and centering means movable in said housing forengagement with said housing and with said indicator means and subjectedto the one supplied fluid pressure, said centering means being urged inresponse to the one supplied fluid pressure acting thereon towardengagement with said housing and said indicator means to oppose movementof said indicator means from its centered position toward the other ofits translated positions in response to the other supplied fluidpressure acting thereon.
 2. A control valve according to claim 1,comprising first and second opposed end portions on said indicator meansmovable in said bypass passage and said housing and subjected to theapplied fluid pressure and the other supplied fluid pressure,respectively, said first end portion normally interrupting pressurefluid communication through said bypass passage between the one suppliedfluid pressure and the applied fluid pressure when said indicator meansis in its centered position, said indicator means being movable to itsone translated position in response to the applied fluid pressure actingon said first end portion upon the failure of the other supplied fluidpressure acting on said second end portion, and said first end portionbeing movable to a bypassing position opening said bypass passage toestablish the pressure fluid communication therethrough between the onesupplied fluid pressure and the applied fluid pressure upon the movementof said indicator means to its one translated position.
 3. A controlvalve according to claim 2, comprising seal means normally engagedbetween said first end portion and said bypass passage to close saidbypass passage and interrupt pressure fluid communication therethroughbetween the one supplied fluid pressure and the applied fluid pressure,said seal means being disengaged from one of said first end portion andsaid bypass passage upon the movement of said first end portion to itsbypassing position.
 4. A control valve according to claim 3, whereinsaid seal means is carried on said first end portion and disengaged fromsaid bypass passage upon the movement of said first end portion to itsbypassing position.
 5. A control valve according to claim 1, comprisingseal means normally engaged between said indicator means and said bypasspassage to close said bypass passage and interrupt pressure fluidcommunication therethrough between the one supplied fluid pressure andthe applied fluid pressure, said seal means being disengaged from one ofsaid indicator means and bypass passage upon the movement of saidindicator means to its one translated position to open said bypasspassage and establish the pressure fluid communication therethroughbetween the one supplied fluid pressure and the applied fluid pressure.6. A control valve according to claim 5, wherein said seal means iscarried on said indicator means and disengaged from said bypass passageupon the movement of said indicator means to its one translatedposition.
 7. A control valve according to claim 1, comprising a pair ofstepped bores in said divider member defining a portion of said flowpassage, said proportioning means being movable in one of said steppedbores, a valve seat on said divider member between said stepped boresfor engagement with said proportioning means, said proportioning meansbeing initially movable to its isolating position into engagement withsaid valve seat to isolate the one supplied fluid pressure in said onestepped bore from the applied fluid pressure in the other of saidstepped bores and being thereafter further movable to its meteringposition disengaged from said valve seat to effect the metered increasein the applied fluid pressure, and said one end of said bypass passagebeing connected with said other stepped bore.
 8. A control valvecomprising a housing, a divider member in said housing and defining withsaid housing a pressure fluid flow passage therethrough for one ofseparate fluid pressures supplied to said housing, a pair of steppedbores in said divider member defining a portion of said flow passage, anannular shoulder on said divider member between said stepped bores,valve seating means about said flow passage and normally engaged withsaid shoulder, a proportioning piston movable in one of said steppedbores and having valve means thereon extending into the other of saidbores for engagement with said valve seating means to control theapplication of the one supplied fluid pressure from said one steppedbore to said other stepped bore, resilient means engaged with saidproportioning piston and normally urging said valve means toward aposition disengaged from said valve seating means, opposed first andsecond effective areas on said proportioning piston for respectivesubjection to the one supplied fluid pressure and the applied fluidpressure, said proportioning piston being initially movable against theforce of said resilient means in response to the one supplied fluidpressure and applied fluid pressure of a predetermined valuerespectively acting on said first and second areas toward a positionengaging said valve means with said seating means and isolating the onesupplied fluid pressure in said one stepped bore from the applied fluidpressure in said other stepped bore, said proportioning piston alsobeing thereafter further movable against the applied fluid pressureacting on said second area in response to increases in the one suppliedfluid pressure acting on said first area and assisted by the force ofsaid resilient means toward a metering position disengaging said valvemeans from said seating means to effect a metered increase in theapplied fluid pressure in a predetermined ratio with the increased onesupplied fluid pressure in excess of the predetermined value, a bypasspassage in said divider member having one end connected with said otherstepped bore and the end thereof subjected to the one supplied fluidpressure, indicator means movable between a centered position andopposed translated positions in said housing for indicating a failure ofthe one supplied fluiD pressure and the other of the supplied fluidpressures including a first end portion movable in said housing andhaving a third effective area thereon subjected to the other suppliedfluid pressure, a second end portion on said indicator means and opposedto said first end portion, said second end portion being movable in saiddivider member for controlling pressure fluid communication through saidbypass passage between the one supplied fluid pressure and applied fluidpressure, a fourth effective area on said second end portion opposed tosaid third area and subjected to the applied fluid pressure, saidindicator means being movable from its centered position toward one ofits translated positions in response to the applied fluid pressureacting on said fourth area in the event of the failure of the othersupplied fluid pressure acting on said third area, and said second endportion being movable toward a bypassing position in said bypass passageestablishing open pressure fluid communication therethrough between theone supplied fluid pressure and the applied fluid pressure in bypassrelation with said proportioning piston to obviate the metering functionthereof when said indicator means is moved to its one translatedposition, a centering piston movable in said housing for engagement withsaid housing and said indicator means, and a fifth area on saidcentering piston opposed to said third are and subjected to the onesupplied fluid pressure, said centering piston being urged in responseto the one supplied fluid pressure acting on said fifth area towardengagement with said housing and said indicator means to oppose movementof said indicator means from its centered position toward the other ofits translated positions in response to the other supplied fluidpressure acting on said third area.
 9. In a split braking system havinga split master cylinder for supplying separate fluid pressures to saidsplit braking system; a control valve comprising a housing adapted toreceive the separate supplied fluid pressures, a divider member in saidhousing and defining therewith inlet and outlet chambers, said inletchamber being subjected to one of the supplied fluid pressures,proportioning means movable in said divider member between said inletand outlet chambers for controlling the application of the one suppliedfluid pressure from said inlet chamber to said outlet chamber, saidproportioning means being initially movable in response to the onesupplied fluid pressure in said inlet chamber and the applied fluidpressure in said outlet chamber of a predetermined value toward aposition isolating the one supplied fluid pressure in said inlet chamberfrom the applied fluid pressure in said outlet chamber and beingthereafter further movable in response to increases in the one suppliedfluid pressure in said inlet chamber toward a metering positioneffecting a metered increase in the applied fluid pressure in saidoutlet chamber in a predetermined ratio with the increased one suppliedfluid pressure in excess of the predetermined value, a bypass passage insaid divider member having one end connected with said outlet chamberand subjected to the applied fluid pressure and the other end thereofconnected with said inlet chamber and subjected to the one suppliedfluid pressure, another inlet chamber in said housing subjected to theother of the supplied fluid pressures, indicator means including an endportion movable in said housing and subjected to the other suppliedfluid pressure in said other inlet chamber, another end portion opposedto said first-named end portion movable in said divider member forcontrolling pressure fluid communication through said said bypasspassage between the one supplied fluid pressure in said first namedinlet chamber and the applied fluid pressure in said outlet chamber,said other end portion being subjected to the applied fluid pressure insaid bypass passage, said indicator means being movable from a normalcentered position toward one of opposeD translated positions in saidhousing in response to the applied fluid pressure acting on said otherend portion in the event of the failure of the other supplied fluidpressure in said other inlet chamber acting on said one end portion, andsaid other end portion being movable toward a position opening saidbypass passage and establishing pressure fluid communicationtherethrough between the one supplied fluid pressure in said first namedinlet chamber and the applied fluid pressure in said outlet chamber inbypass relation with said proportioning means to obviate the meteringactuation thereof when said indicator means is moved to its onetranslated position, and centering means movable in said housing forengagement with said housing and said indicator means and subjected tothe one supplied fluid pressure in said first-named inlet chamber, saidcentering means being urged in response to the one supplied fluidpressure in said first named inlet chamber acting thereon towardengagement with said housing and with said indicator means to opposemovement of said indicator means from its centered position toward theother of its translated positions in response to the other suppliedfluid pressure in said other inlet chamber acting on said one endportion.
 10. A control valve comprising a housing having a pair of inletports and an outlet port, a divider member in said housing includingpassage means connected between one of said inlet ports and said outletport, proportioning means movable in said passage means for controllingthe application of fluid pressure therethrough from said one inlet portto said outlet port, said proportioning means being initially movable inresponse to fluid pressures at said one inlet port and said outlet portof a predetermined value toward a position in said passage meansisolating the respective fluid pressures at said one inlet port and saidoutlet port and being thereafter further movable in response toincreases in the fluid pressure at said one inlet port toward a meteringposition effecting a metered increase in the fluid pressure at saidoutlet port in a predetermined ratio with the increased fluid pressureat said one inlet port, and bypass passage means in said divider memberhaving one end connected with said first named passage means andsubjected to the fluid pressure at said outlet port and the other endthereof connected with said one inlet port, indicator means including anend portion movable in said housing and subjected to the fluid pressureat the other of said inlet ports, another end portion opposed to saidfirst named end portion movable in said divider member for controllingpressure fluid communication through said bypass passage means betweensaid one inlet port and said outlet port and subjected to the fluidpressure at said outlet port, said indicator means being movable from anormal centered position toward one of opposed translated positions insaid housing in response to the fluid pressure at said outlet portacting on said other end portion in the event of the failure of thefluid pressure at said other inlet port acting on said one end portion,and said other end portion being movable toward a position in saidbypass passage establishing open pressure fluid communicationtherethrough between the fluid pressures at said one inlet port and saidoutlet port in bypass relation with said proportioning means to obviatethe metering actuation thereof when said indicator means is moved to itsone translated position, and centering means movable in said housing forengagement with said housing and said indicator means and subjected tothe fluid pressure at said one inlet port, said centering means beingurged in response to the fluid pressure at said one inlet port actingthereon toward engagement with said housing and with said indicatormeans to oppose movement of said indicator means from its centeredposition toward the other of its translated positions in response to thefluid pressure at said other inlet port acting oN said one end portion.